CVE-2025-11777: mattermost server Auth Bypass — Fix

Description

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint

Is your site exposed to CVE-2025-11777?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Weakness Type (CWE)

CWE-863 Incorrect Authorization

Affected Products

Vendor	Product	Versions
mattermost	mattermost_server	10.5.0 — 10.5.12
mattermost	mattermost_server	10.11.0 — 10.11.4

References

Advisories & Patches

https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2025-11777? +

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint It has a CVSS v3.1 base score of 3.1 (LOW).

How severe is CVE-2025-11777? +

CVE-2025-11777 has a CVSS v3.1 score of 3.1 out of 10, rated LOW. This is a low-severity vulnerability with limited impact.

What products are affected by CVE-2025-11777? +

CVE-2025-11777 affects products from mattermost, specifically: mattermost_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-11777? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-84355

Incorrect authorization in Navigation in Google Chrome prior to 152.0.7977.75 allowed a remote attacker who had compromised the renderer process …

CVE-2026-65601

Traefik versions 3.7.0 through 3.7.6 contain a namespace confusion vulnerability in the Kubernetes Gateway API provider. When resolving HTTPRoute.spec.rules[].backendRefs[].filters[].extensionRef, Traefik …

CVE-2026-50008

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. From version …

CVE-2026-105851

Payload is a free and open source headless content management system. In versions from 3.0.0 before 3.90.0 and canary versions …

CVE-2026-15829

A SQL injection (CWE-89) and security boundary bypass (CWE-863) vulnerability exists in the prebuilt BigQuery forecasting tool (bigquery-forecast) of googleapis/mcp-toolbox. …

CVE-2026-97147

In OpenStack Mistral through 23.0.0, several of the v2 API write paths resolve the target object with a query that …

CVE-2025-11777